Analyzing the Stability and Interactions of GQuadruplex and G-Triplex DNA in Drug Systems by Using Novel Optical Spectroscopy Techniques
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There have been studies that demonstrate the existence of non-canonical DNA such as G-Quadruplex and G-Triplex within the human body. These structures tend to serve biological roles within telomeres and other DNA systems. G-Quadruplex and Triplex structure in the telomeres have shown to be anticancerous by preventing the rapid replication of cancer cells. However, one needs to stabilize the G-quadruplex and G-triplex DNA structures to stop replication, which is the main motivation of the present work. In our approach, we analyzed the stability of the G-Quadruplex and G-Triplex with different drug systems in order to understand which drugs made these non-canonical DNA systems more stable and how they bind to the DNA backbone. In this process, we propose to establish new spectroscopic technique based on relative twophoton absorption that can monitor drug-DNA binding interactions. For these studies, temperature-dependent UV-Vis, 1-photon and 2-photon fluorescence, circular dichroism, and relative 2-photon cross-sections were carried out. Most important among them is the utilization of the relative 2-photon cross-section in monitoring the binding orientation of the drug relative to the DNA backbone. Interesting stability trends were obtained that can be correlated with the structure of the drug and DNA binding modes. More experiments are needed to establish more inroads into 2PA cross-section techniques such as fluorescence anisotropy to see another perspective of drug binding.